Most rooms with an area intended for seating an audience, such as a theatre or a cinema hall, are furnished with rows of retractable chairs, which spontaneously hold the seat on an upright position at a standby elevation when not in use, and allow rotating and lowering the seat to a supporting elevation in order to use it as a physical support.
This type of retracting behaviour aims at providing free space when the rotating part is not being used. This has practical advantages, for example an improved manoeuvring space for allowing users to walk around without colliding with the rotating seat, or a better access for cleaning purposes of the surface beneath the rotating part.
This type of mechanical behaviour is also known from many other applications besides seats, such as armrests, tables or shelves.
In order for the known solutions to allow movement of the rotating part onto the supporting state, they merely block the rotating part from rotating down more than a certain elevation, or pitch, angle. Since the force that is supported, e.g. a user's weight, has the same direction of the rotation to move the rotating part to the supporting state, the approach of merely allowing the rotation until a certain elevation angle and then blocking it, is the known solution in these cases. Document DE 202005017771 U1 describes a collapsible chair for a sports stadium, in which, when extended out of a protecting box, there is provided an object similar to a retractable chair. In that state, the movement of the seat to the supporting state has the same direction of the weight that can be supported, and, at an elevation angle corresponding to the supporting state, the seat is obstructed from hinging down any more.